Question: do you think there is a reason why humans came on the earth so late?

Ian van der Linde answered on 11 Jun 2011:

The thing that makes humans different from other animals is our big brains. These take a very long time to evolve, because they are so incredibly complicated. The human brain is by far the most complex object in the Universe (there are as many brain cells in your head as there are stars in our Galaxy – about 100 billion!). Our brains can perform processing tasks in the blink of an eye that that no computer yet invented is capable of.

The chance of any one genetic mutation causing an improvement to an animal is so tiny, especially when the organ taking the brunt of the mutation is as complex as the brain. This means that even living in an environment where being clever makes you more likely to survive will mean that it will take millions of years for a big-brained animal to evolve. And before this could happen, lots of preliminary evolution needs to have taken place – from pools of amino acids, to single celled organisms, to aquatic creatures, through to reptiles, then to mammals, then to primates and so on. Changes that are so dramatic take an incredibly long time to take place — remember that you are distantly related to a creature like an amoeba, and think how many changes you’d need to make to an amoeba to make it into a person!